SB421RG, 30 amp, 240 volt, 3 phase, 4 wire, with ground, fusible style bus plug, type BEB / SB, UL Listed assembly, complete with UL Recognized internal switch and components, suitable for use with OEM Spectra Series industrial busway systems, accepts Class H, R and J fuse types, direct substitute, fit and function for OEM SB421RG, SB421RGR, SB421RGJ